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Erhart T, Nadegger C, Vergeiner S, Kreutz C, Müller T, Kräutler B. Novel Types of Phyllobilins in a Fern - Molecular Reporters of the Evolution of Chlorophyll Breakdown in the Paleozoic Era. Chemistry 2024:e202401288. [PMID: 38634697 DOI: 10.1002/chem.202401288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Accepted: 04/17/2024] [Indexed: 04/19/2024]
Abstract
Breakdown of chlorophyll (Chl), as studied in angiosperms, follows the pheophorbide a oxygenase/phyllobilin (PaO/PB) pathway, furnishing linear tetrapyrroles, named phyllobilins (PBs). In an investigation with fern leaves we have discovered iso-phyllobilanones (iPBs) with an intriguingly rearranged and oxidized carbon skeleton. We report here a key second group of iPBs from the fern and on their structure analysis. Previously, these additional Chl-catabolites escaped their characterization, since they exist in aqueous media as mixtures of equilibrating isomers. However, their chemical dehydration furnished stable iPB-derivatives that allowed the delineation of the enigmatic structures and chemistry of the original natural catabolites. The structures of all fern-iPBs reflect the early core steps of a PaO/PB-type pathway and the PB-to-iPB carbon skeleton rearrangement. A striking further degradative chemical ring-cleavage was observed, proposed to consume singlet molecular oxygen (1O2). Hence, Chl-catabolites may play a novel active role in detoxifying cellular 1O2. The critical deviations from the PaO/PB pathway, found in the fern, reflect evolutionary developments of Chl-breakdown in the green plants in the Paleozoic era.
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Affiliation(s)
- Theresia Erhart
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
| | - Christian Nadegger
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
| | - Stefan Vergeiner
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
| | - Thomas Müller
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
| | - Bernhard Kräutler
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
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2
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Altaf F, Parveen S, Farooq S, Ul Haq A, Lone ML, Tahir I, Kaushik P, El-Serehy HA. Polyamines effectively mitigate senescence in persistent leaves of Berginia ciliata - a novel model system. FUNCTIONAL PLANT BIOLOGY : FPB 2023; 50:136-145. [PMID: 35144727 DOI: 10.1071/fp21273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
Plant leaves provide a unique insight into the changes that occur in organs, tissues and cells as they approach senescence. As part of the parental outlay, plants instigate leaf senescence to reallocate resources from older tissues to new organs towards the termination of the growing season. The aim of crop breeding initiatives is to optimize senescence for specific species. Considering hormonal regulation and their crosstalk during leaf senescence through integration of developmental signals, this work examines the efficacy of polyamines (PAs) in modulating several biochemical and physiological aspects with an ultimate aim to delay leaf senescence in leaf discs of Berginia ciliata (Haw.) sternb. Leaf discs were treated with putrescine (Put), spermidine (Spd) and spermine (Spm) at 20μM, 20μM and 15μM concentration, respectively. A set of leaf discs kept in distilled water served as the control. Leaf discs treated with PAs were green and fresh by about 4 days compared to the control, thus exhibited delayed senescence. This delayed leaf senescence corroborated with the maintenance of high activity of reactive oxygen species (ROS) scavenging antioxidant enzymes viz , superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and higher content of chlorophylls. A marked increase was also observed in membrane stability and soluble proteins in leaf discs treated with PAs. Exogenous PAs reduced oxidative stress in the leaf discs, as revealed by lower malondialdehyde (MDA) level, which is manifested as reduced lipid peroxidation (LPO). Improved membrane stability was proportional to lower LPO, as measured by the membrane stability index (MSI).
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Affiliation(s)
- Foziya Altaf
- Plant Physiology and Biochemistry Research Laboratory, Department of Botany, University of Kashmir, Srinagar 190006, India
| | - Shazia Parveen
- Plant Physiology and Biochemistry Research Laboratory, Department of Botany, University of Kashmir, Srinagar 190006, India
| | - Sumira Farooq
- Plant Physiology and Biochemistry Research Laboratory, Department of Botany, University of Kashmir, Srinagar 190006, India
| | - Aehsan Ul Haq
- Plant Physiology and Biochemistry Research Laboratory, Department of Botany, University of Kashmir, Srinagar 190006, India
| | - Mohammad Lateef Lone
- Plant Physiology and Biochemistry Research Laboratory, Department of Botany, University of Kashmir, Srinagar 190006, India
| | - Inayatullah Tahir
- Plant Physiology and Biochemistry Research Laboratory, Department of Botany, University of Kashmir, Srinagar 190006, India
| | - Prashant Kaushik
- Instituto de Conservación y Mejora de la Agrodiversidad Valenciana, Universitat Politècnica de València, 46022 Valencia, Spain
| | - Hamed A El-Serehy
- Department of Zoology, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
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3
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Lin YP, Shen YY, Shiu YB, Charng YY, Grimm B. Chlorophyll dephytylase 1 and chlorophyll synthase: a chlorophyll salvage pathway for the turnover of photosystems I and II. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 111:979-994. [PMID: 35694901 DOI: 10.1111/tpj.15865] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/02/2022] [Indexed: 06/15/2023]
Abstract
Chlorophyll (Chl) is made up of the tetrapyrrole chlorophyllide and phytol, a diterpenoid alcohol. The photosynthetic protein complexes utilize Chl for light harvesting to produce biochemical energy for plant development. However, excess light and adverse environmental conditions facilitate generation of reactive oxygen species, which damage photosystems I and II (PSI and PSII) and induce their turnover. During this process, Chl is released, and is thought to be recycled via dephytylation and rephytylation. We previously demonstrated that Chl recycling in Arabidopsis under heat stress is mediated by the enzymes chlorophyll dephytylase 1 (CLD1) and chlorophyll synthase (CHLG) using chlg and cld1 mutants. Here, we show that the mutants with high CLD1/CHLG ratio, by different combinations of chlg-1 (a knock-down mutant) and the hyperactive cld1-1 alleles, develop necrotic leaves when grown under long- and short-day, but not continuous light conditions, owing to the accumulation of chlorophyllide in the dark. Combination of chlg-1 with cld1-4 (a knock-out mutant) leads to reduced chlorophyllide accumulation and necrosis. The operation of CLD1 and CHLG as a Chl salvage pathway was also explored in the context of Chl recycling during the turnover of Chl-binding proteins of the two photosystems. CLD1 was found to interact with CHLG and the light-harvesting complex-like proteins OHP1 and LIL3, implying that auxiliary factors are required for this process.
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Affiliation(s)
- Yao-Pin Lin
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstraße 13 Building 12, 10115, Berlin, Germany
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan, ROC
| | - Yu-Yen Shen
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan, ROC
| | - Yen-Bin Shiu
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan, ROC
| | - Yee-Yung Charng
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 11529, Taiwan, ROC
| | - Bernhard Grimm
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstraße 13 Building 12, 10115, Berlin, Germany
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4
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Research Progress in the Interconversion, Turnover and Degradation of Chlorophyll. Cells 2021; 10:cells10113134. [PMID: 34831365 PMCID: PMC8621299 DOI: 10.3390/cells10113134] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/06/2021] [Accepted: 11/08/2021] [Indexed: 01/01/2023] Open
Abstract
Chlorophylls (Chls, Chl a and Chl b) are tetrapyrrole molecules essential for photosynthetic light harvesting and energy transduction in plants. Once formed, Chls are noncovalently bound to photosynthetic proteins on the thylakoid membrane. In contrast, they are dismantled from photosystems in response to environmental changes or developmental processes; thus, they undergo interconversion, turnover, and degradation. In the last twenty years, fruitful research progress has been achieved on these Chl metabolic processes. The discovery of new metabolic pathways has been accompanied by the identification of enzymes associated with biochemical steps. This article reviews recent progress in the analysis of the Chl cycle, turnover and degradation pathways and the involved enzymes. In addition, open questions regarding these pathways that require further investigation are also suggested.
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Tian YN, Zhong RH, Wei JB, Luo HH, Eyal Y, Jin HL, Wu LJ, Liang KY, Li YM, Chen SZ, Zhang ZQ, Pang XQ. Arabidopsis CHLOROPHYLLASE 1 protects young leaves from long-term photodamage by facilitating FtsH-mediated D1 degradation in photosystem II repair. MOLECULAR PLANT 2021; 14:1149-1167. [PMID: 33857689 DOI: 10.1016/j.molp.2021.04.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 04/01/2021] [Accepted: 04/08/2021] [Indexed: 06/12/2023]
Abstract
The proteolytic degradation of the photodamaged D1 core subunit during the photosystem II (PSII) repair cycle is well understood, but chlorophyll turnover during D1 degradation remains unclear. Here, we report that Arabidopsis thaliana CHLOROPHYLLASE 1 (CLH1) plays important roles in the PSII repair process. The abundance of CLH1 and CLH2 peaks in young leaves and is induced by high-light exposure. Seedlings of clh1 single and clh1-1/2-2 double mutants display increased photoinhibition after long-term high-light exposure, whereas seedlings overexpressing CLH1 have enhanced light tolerance compared with the wild type. CLH1 is localized in the developing chloroplasts of young leaves and associates with the PSII-dismantling complexes RCC1 and RC47, with a preference for the latter upon exposure to high light. Furthermore, degradation of damaged D1 protein is retarded in young clh1-1/2-2 leaves after 18-h high-light exposure but is rescued by the addition of recombinant CLH1 in vitro. Moreover, overexpression of CLH1 in a variegated mutant (var2-2) that lacks thylakoid protease FtsH2, with which CLH1 interacts, suppresses the variegation and restores D1 degradation. A var2-2 clh1-1/2-2 triple mutant shows more severe variegation and seedling death. Taken together, these results establish CLH1 as a long-sought chlorophyll dephytylation enzyme that is involved in PSII repair and functions in long-term adaptation of young leaves to high-light exposure by facilitating FtsH-mediated D1 degradation.
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Affiliation(s)
- Ya-Nan Tian
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables, South China Agricultural University, Guangzhou 510642, People's Republic of China; College of Life Sciences, South China Agricultural University, Guangzhou 510642, People's Republic of China
| | - Rui-Hao Zhong
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables, South China Agricultural University, Guangzhou 510642, People's Republic of China; College of Life Sciences, South China Agricultural University, Guangzhou 510642, People's Republic of China
| | - Jun-Bin Wei
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables, South China Agricultural University, Guangzhou 510642, People's Republic of China; College of Life Sciences, South China Agricultural University, Guangzhou 510642, People's Republic of China
| | - Hong-Hui Luo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables, South China Agricultural University, Guangzhou 510642, People's Republic of China; College of Horticulture, South China Agricultural University, Guangzhou 510642, People's Republic of China
| | - Yoram Eyal
- Institute of Plant Sciences, The Volcani Center, Agricultural Research Organization, Bet Dagan 50250, Israel
| | - Hong-Lei Jin
- Institute of Medical Plant Physiology and Ecology, School of Pharmaceutical Sciences, Guangzhou University of Chinese Medicine, Guangzhou 510006, People's Republic of China
| | - La-Jie Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables, South China Agricultural University, Guangzhou 510642, People's Republic of China; College of Life Sciences, South China Agricultural University, Guangzhou 510642, People's Republic of China
| | - Ke-Ying Liang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables, South China Agricultural University, Guangzhou 510642, People's Republic of China; College of Life Sciences, South China Agricultural University, Guangzhou 510642, People's Republic of China
| | - Ying-Man Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables, South China Agricultural University, Guangzhou 510642, People's Republic of China; College of Life Sciences, South China Agricultural University, Guangzhou 510642, People's Republic of China
| | - Shu-Zhen Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables, South China Agricultural University, Guangzhou 510642, People's Republic of China; College of Life Sciences, South China Agricultural University, Guangzhou 510642, People's Republic of China
| | - Zhao-Qi Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables, South China Agricultural University, Guangzhou 510642, People's Republic of China; College of Horticulture, South China Agricultural University, Guangzhou 510642, People's Republic of China.
| | - Xue-Qun Pang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables, South China Agricultural University, Guangzhou 510642, People's Republic of China; College of Life Sciences, South China Agricultural University, Guangzhou 510642, People's Republic of China.
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Aubry S, Christ B, Kräutler B, Martinoia E, Thomas H, Zipfel C. An evergreen mind and a heart for the colors of fall. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:4625-4633. [PMID: 33860301 PMCID: PMC8219035 DOI: 10.1093/jxb/erab162] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 04/11/2021] [Indexed: 06/01/2023]
Abstract
With the finest biochemical and molecular approaches, convincing explorative strategies, and long-term vision, Stefan Hörtensteiner succeeded in elucidating the biochemical pathway responsible for chlorophyll degradation. After having contributed to the identification of key chlorophyll degradation products in the course of the past 25 years, he gradually identified and characterized most of the crucial players in the PAO/phyllobilin degradation pathway of chlorophyll. He was one of the brightest plant biochemists of his generation, and his work opened doors to a better understanding of plant senescence, tetrapyrrole homeostasis, and their complex regulation. He sadly passed away on 5 December 2020, aged 57.
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Affiliation(s)
- Sylvain Aubry
- Department of Plant and Microbial Biology, University of Zürich, Zürich, Switzerland
| | - Bastien Christ
- Berries and Medicinal Plants, Plant Production Systems, Agroscope, Conthey, Switzerland
| | - Bernhard Kräutler
- Institute of Organic Chemistry & Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Enrico Martinoia
- Department of Plant and Microbial Biology, University of Zürich, Zürich, Switzerland
| | - Howard Thomas
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth, Wales, UK
| | - Cyril Zipfel
- Department of Plant and Microbial Biology, University of Zürich, Zürich, Switzerland
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7
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Wang P, Karg CA, Frey N, Frädrich J, Vollmar AM, Moser S. Phyllobilins as a challenging diverse natural product class: Exploration of pharmacological activities. Arch Pharm (Weinheim) 2021; 354:e2100061. [PMID: 34155668 DOI: 10.1002/ardp.202100061] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 05/26/2021] [Accepted: 05/31/2021] [Indexed: 11/08/2022]
Abstract
Phyllobilins are a group of chlorophyll-derived bilin-type linear tetrapyrroles, generated in the process of chlorophyll breakdown. Since the first phyllobilin was isolated and characterized in 1991, more and more structures of these chlorophyll catabolites were identified alongside the biochemical players involved in chlorophyll breakdown. In the meantime, phyllobilins are known to occur in a large natural structural variety, and new modifications are still being discovered. Phyllobilins have been regarded as products of chlorophyll detoxification for a very long time, hence they have been completely overlooked as a natural product class in terms of their biological role or pharmacological activity. A change of this paradigm, however, is long overdue. Here, we review the current knowledge of the pharmacological activities of phyllobilins and give an overview of the diverse structural modifications, laying the groundwork for analyzing their role(s) as active components in medicinal plants.
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Affiliation(s)
- Pengyu Wang
- Pharmaceutical Biology, Department of Pharmacy, Ludwig-Maximilians University of Munich, Munich, Germany
| | - Cornelia A Karg
- Pharmaceutical Biology, Department of Pharmacy, Ludwig-Maximilians University of Munich, Munich, Germany
| | - Nadine Frey
- Pharmaceutical Biology, Department of Pharmacy, Ludwig-Maximilians University of Munich, Munich, Germany
| | - Julian Frädrich
- Pharmaceutical Biology, Department of Pharmacy, Ludwig-Maximilians University of Munich, Munich, Germany
| | - Angelika M Vollmar
- Pharmaceutical Biology, Department of Pharmacy, Ludwig-Maximilians University of Munich, Munich, Germany
| | - Simone Moser
- Pharmaceutical Biology, Department of Pharmacy, Ludwig-Maximilians University of Munich, Munich, Germany
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8
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Karg CA, Doppler C, Schilling C, Jakobs F, Dal Colle MCS, Frey N, Bernhard D, Vollmar AM, Moser S. A yellow chlorophyll catabolite in leaves of Urtica dioica L.: An overlooked phytochemical that contributes to health benefits of stinging nettle. Food Chem 2021; 359:129906. [PMID: 33962192 DOI: 10.1016/j.foodchem.2021.129906] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 03/19/2021] [Accepted: 04/16/2021] [Indexed: 10/21/2022]
Abstract
Stinging nettle is appreciated for its antioxidant and anti-inflammatory properties, which renders the plant a popular ingredient in a healthy diet in form of salads or smoothies. The most common use, presumably, is of dried leaves as ingredient in tea mixtures. The plant's health benefits are attributed primarily to phenolic phytochemicals. Here we describe the characterization and quantification of a phylloxanthobilin (PxB), a yellow chlorophyll catabolite, in nettle tea. Despite their abundance in the plant kingdom, chlorophyll catabolites have been overlooked as phytochemicals and as part of human nutrition. Our investigations of tea reveal that one cup of nettle tea contains about 50 µg of PxB with large variations depending on the supplier. When investigating the bioactivities of PxB, our observations show that PxB has antioxidative and anti-inflammatory activities comparable to known bioactive small molecules found in nettle, indicating the phylloxanthobilin to be an overlooked ingredient of nettle tea.
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Affiliation(s)
- Cornelia A Karg
- Department of Pharmacy, Center for Drug Research, Pharmaceutical Biology, Ludwig-Maximilians-University of Munich, Butenandtstr. 5-13, D-81377 München, Germany
| | - Christian Doppler
- Division of Pathophysiology, Institute of Physiology and Pathophysiology, Medical Faculty, Johannes-Kepler-University Linz, Krankenhausstrasse 7a, A-4020 Linz, Austria
| | - Charlotte Schilling
- Department of Pharmacy, Center for Drug Research, Pharmaceutical Biology, Ludwig-Maximilians-University of Munich, Butenandtstr. 5-13, D-81377 München, Germany
| | - Franziska Jakobs
- Department of Pharmacy, Center for Drug Research, Pharmaceutical Biology, Ludwig-Maximilians-University of Munich, Butenandtstr. 5-13, D-81377 München, Germany; Department of Chemistry, High Point University, One University Parkway High Point, NC 27268, United States
| | - Marlene C S Dal Colle
- Department of Pharmacy, Center for Drug Research, Pharmaceutical Biology, Ludwig-Maximilians-University of Munich, Butenandtstr. 5-13, D-81377 München, Germany; Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
| | - Nadine Frey
- Department of Pharmacy, Center for Drug Research, Pharmaceutical Biology, Ludwig-Maximilians-University of Munich, Butenandtstr. 5-13, D-81377 München, Germany
| | - David Bernhard
- Division of Pathophysiology, Institute of Physiology and Pathophysiology, Medical Faculty, Johannes-Kepler-University Linz, Krankenhausstrasse 7a, A-4020 Linz, Austria
| | - Angelika M Vollmar
- Department of Pharmacy, Center for Drug Research, Pharmaceutical Biology, Ludwig-Maximilians-University of Munich, Butenandtstr. 5-13, D-81377 München, Germany
| | - Simone Moser
- Department of Pharmacy, Center for Drug Research, Pharmaceutical Biology, Ludwig-Maximilians-University of Munich, Butenandtstr. 5-13, D-81377 München, Germany.
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9
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Lin YP, Charng YY. Chlorophyll dephytylation in chlorophyll metabolism: a simple reaction catalyzed by various enzymes. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 302:110682. [PMID: 33288004 DOI: 10.1016/j.plantsci.2020.110682] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 08/12/2020] [Accepted: 09/14/2020] [Indexed: 05/21/2023]
Abstract
Chlorophyll (Chl) is composed of a tetrapyrrole ring and a phytol tail, which facilitate light energy absorbance and assembly with photosynthetic protein complexes, respectively. Chl dephytylation, the hydrolytic removal of the phytol tail, is considered a pivotal step in diverse physiological processes, such as Chl salvage during repair of the photosystem, the Chl cycle in the adjustment of antenna size, and Chl breakdown in leaf senescence and fruit maturation. Moreover, phytol is a component of the tocopherols, a major form of vitamin E that is essential in the human diet. This phytol mostly comes from Chl hydrolysis. However, the authentic enzyme responsible for Chl dephytylation has proved elusive. CHLOROPHYLLASE (CLH) which was discovered over a century ago, was the first enzyme found to have dephytylation activity in vitro, but its role in Chl metabolism has been questioned and remains under debate. Recently, novel dephytylases, i.e., PHEOPHYTINASE (PPH) and CHLOROPHYLL DEPHYTYLASE1 (CLD1) have emerged from genetic studies, indicating that dephytylation in Chl catabolism involves different players and is more complicated than previously thought. Based on sequence homology, substrate specificity, and subcellular localization, CLH, PPH, and CLD1 belong to different types of dephytylase, which prompted us to re-examine the dilemmas and missing links that still exist in Chl metabolism. This review thus focuses on the hitherto unanswered questions involving the Chl dephytylation reaction by highlighting relevant literature, updating recent progress, and synthesizing ideas.
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Affiliation(s)
- Yao-Pin Lin
- Institut of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Germany; Agricultural Biotechnology Research Center, Academia Sinica, Taiwan, ROC.
| | - Yee-Yung Charng
- Agricultural Biotechnology Research Center, Academia Sinica, Taiwan, ROC.
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10
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Wang P, Richter AS, Kleeberg JRW, Geimer S, Grimm B. Post-translational coordination of chlorophyll biosynthesis and breakdown by BCMs maintains chlorophyll homeostasis during leaf development. Nat Commun 2020; 11:1254. [PMID: 32198392 PMCID: PMC7083845 DOI: 10.1038/s41467-020-14992-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 02/11/2020] [Indexed: 12/20/2022] Open
Abstract
Chlorophyll is indispensable for life on Earth. Dynamic control of chlorophyll level, determined by the relative rates of chlorophyll anabolism and catabolism, ensures optimal photosynthesis and plant fitness. How plants post-translationally coordinate these two antagonistic pathways during their lifespan remains enigmatic. Here, we show that two Arabidopsis paralogs of BALANCE of CHLOROPHYLL METABOLISM (BCM) act as functionally conserved scaffold proteins to regulate the trade-off between chlorophyll synthesis and breakdown. During early leaf development, BCM1 interacts with GENOMES UNCOUPLED 4 to stimulate Mg-chelatase activity, thus optimizing chlorophyll synthesis. Meanwhile, BCM1’s interaction with Mg-dechelatase promotes degradation of the latter, thereby preventing chlorophyll degradation. At the onset of leaf senescence, BCM2 is up-regulated relative to BCM1, and plays a conserved role in attenuating chlorophyll degradation. These results support a model in which post-translational regulators promote chlorophyll homeostasis by adjusting the balance between chlorophyll biosynthesis and breakdown during leaf development. Plants regulate chlorophyll levels to optimise photosynthesis. Here Wang et al. describe two paralogous thylakoid proteins, BCM1 and BCM2, which stimulate chlorophyll biosynthesis and attenuate chlorophyll degradation respectively through interaction with the Mg-chelatase-stimulating factor GUN4 and Mg-dechelatase isoform SGR1.
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Affiliation(s)
- Peng Wang
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstraße 13, 10115, Berlin, Germany.
| | - Andreas S Richter
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstraße 13, 10115, Berlin, Germany.,Institute of Biology/Physiology of Plant Cell Organelles, Humboldt-Universität zu Berlin, Philippstraße 13, 10115, Berlin, Germany
| | - Julius R W Kleeberg
- Zellbiologie/Elektronenmikroskopie, Universität Bayreuth, 95440, Bayreuth, Germany
| | - Stefan Geimer
- Zellbiologie/Elektronenmikroskopie, Universität Bayreuth, 95440, Bayreuth, Germany
| | - Bernhard Grimm
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstraße 13, 10115, Berlin, Germany.
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11
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Yuan J, Sun X, Guo T, Chao Y, Han L. Global transcriptome analysis of alfalfa reveals six key biological processes of senescent leaves. PeerJ 2020; 8:e8426. [PMID: 32002335 PMCID: PMC6979412 DOI: 10.7717/peerj.8426] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 12/18/2019] [Indexed: 11/20/2022] Open
Abstract
Leaf senescence is a complex organized developmental stage limiting the yield of crop plants, and alfalfa is an important forage crop worldwide. However, our understanding of the molecular mechanism of leaf senescence and its influence on biomass in alfalfa is still limited. In this study, RNA sequencing was utilized to identify differentially expressed genes (DEGs) in young, mature, and senescent leaves, and the functions of key genes related to leaf senescence. A total of 163,511 transcripts and 77,901 unigenes were identified from the transcriptome, and 5,133 unigenes were differentially expressed. KEGG enrichment analyses revealed that ribosome and phenylpropanoid biosynthesis pathways, and starch and sucrose metabolism pathways are involved in leaf development and senescence in alfalfa. GO enrichment analyses exhibited that six clusters of DEGs are involved in leaf morphogenesis, leaf development, leaf formation, regulation of leaf development, leaf senescence and negative regulation of the leaf senescence biological process. The WRKY and NAC families of genes mainly consist of transcription factors that are involved in the leaf senescence process. Our results offer a novel interpretation of the molecular mechanisms of leaf senescence in alfalfa.
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Affiliation(s)
- Jianbo Yuan
- College of Grassland Science, Beijing Forestry University, Beijing, China
| | - Xinbo Sun
- College of Agronomy, Hebei Agricultural University, Key Laboratory of Crop Growth Regulation of Hebei Province, China
| | - Tao Guo
- College of Grassland Science, Beijing Forestry University, Beijing, China
| | - Yuehui Chao
- College of Grassland Science, Beijing Forestry University, Beijing, China
| | - Liebao Han
- College of Grassland Science, Beijing Forestry University, Beijing, China
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