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Homma M, Wakabayashi T, Moriwaki Y, Shiotani N, Shigeta T, Isobe K, Okazawa A, Ohta D, Terada T, Shimizu K, Mizutani M, Takikawa H, Sugimoto Y. Insights into stereoselective ring formation in canonical strigolactone: Identification of a dirigent domain-containing enzyme catalyzing orobanchol synthesis. Proc Natl Acad Sci U S A 2024; 121:e2313683121. [PMID: 38905237 PMCID: PMC11214005 DOI: 10.1073/pnas.2313683121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 04/30/2024] [Indexed: 06/23/2024] Open
Abstract
Strigolactones (SLs) are plant apocarotenoids with diverse roles and structures. Canonical SLs, widespread and characterized by structural variations in their tricyclic lactone (ABC-ring), are classified into two types based on C-ring configurations. The steric C-ring configuration emerges during the BC-ring closure, downstream of the biosynthetic intermediate, carlactonoic acid (CLA). Most plants produce either type of canonical SLs stereoselectively, e.g., tomato (Solanum lycopersicum) yields orobanchol with an α-oriented C-ring. The mechanisms driving SL structural diversification are partially understood, with limited insight into functional implications. Furthermore, the exact molecular mechanism for the stereoselective BC-ring closure reaction is yet to be known. We identified an enzyme, the stereoselective BC-ring-forming factor (SRF), from the dirigent protein (DIR) family, specifically the DIR-f subfamily, whose biochemical function had not been characterized, making it a key enzyme in stereoselective canonical SL biosynthesis with the α-oriented C-ring. We first confirm the precise catalytic function of the tomato cytochrome P450 SlCYP722C, previously shown to be involved in orobanchol biosynthesis [T. Wakabayashi et al., Sci. Adv. 5, eaax9067 (2019)], to convert CLA to 18-oxocarlactonoic acid. We then show that SRF catalyzes the stereoselective BC-ring closure reaction of 18-oxocarlactonoic acid, forming orobanchol. Our methodology combines experimental and computational techniques, including SRF structure prediction and conducting molecular dynamics simulations, suggesting a catalytic mechanism based on the conrotatory 4π-electrocyclic reaction for the stereoselective BC-ring formation in orobanchol. This study sheds light on the molecular basis of how plants produce SLs with specific stereochemistry in a controlled manner.
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Affiliation(s)
- Masato Homma
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe657-8501, Japan
| | - Takatoshi Wakabayashi
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe657-8501, Japan
| | - Yoshitaka Moriwaki
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo113-8657, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo113-8657, Japan
| | - Nanami Shiotani
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo113-8657, Japan
| | - Takumi Shigeta
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo113-8657, Japan
| | - Kazuki Isobe
- Department of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai599-8531, Japan
| | - Atsushi Okazawa
- Department of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai599-8531, Japan
- Department of Agricultural Biology, Graduate School of Agriculture, Osaka Metropolitan University, Sakai599-8531, Japan
| | - Daisaku Ohta
- Department of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai599-8531, Japan
- Department of Agricultural Biology, Graduate School of Agriculture, Osaka Metropolitan University, Sakai599-8531, Japan
| | - Tohru Terada
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo113-8657, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo113-8657, Japan
| | - Kentaro Shimizu
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo113-8657, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo113-8657, Japan
| | - Masaharu Mizutani
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe657-8501, Japan
| | - Hirosato Takikawa
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo113-8657, Japan
| | - Yukihiro Sugimoto
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe657-8501, Japan
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Daignan-Fornier S, Keita A, Boyer FD. Chemistry of Strigolactones, Key Players in Plant Communication. Chembiochem 2024; 25:e202400133. [PMID: 38607659 DOI: 10.1002/cbic.202400133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 04/12/2024] [Accepted: 04/12/2024] [Indexed: 04/13/2024]
Abstract
Today, the use of artificial pesticides is questionable and the adaptation to global warming is a necessity. The promotion of favorable natural interactions in the rhizosphere offers interesting perspectives for changing the type of agriculture. Strigolactones (SLs), the latest class of phytohormones to be discovered, are also chemical mediators in the rhizosphere. We present in this review the diversity of natural SLs, their analogs, mimics, and probes essential for the biological studies of this class of compounds. Their biosynthesis and access by organic synthesis are highlighted especially concerning noncanonical SLs, the more recently discovered natural SLs. Organic synthesis of analogs, stable isotope-labeled standards, mimics, and probes are also reviewed here. In the last part, the knowledge about the SL perception is described as well as the different inhibitors of SL receptors that have been developed.
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Affiliation(s)
- Suzanne Daignan-Fornier
- Institut de Chimie des Substances Naturelles, UPR 2301, Université Paris-Saclay, CNRS, 91198, Gif-sur-Yvette, France
| | - Antoinette Keita
- Institut de Chimie des Substances Naturelles, UPR 2301, Université Paris-Saclay, CNRS, 91198, Gif-sur-Yvette, France
| | - François-Didier Boyer
- Institut de Chimie des Substances Naturelles, UPR 2301, Université Paris-Saclay, CNRS, 91198, Gif-sur-Yvette, France
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Homma M, Uchida K, Wakabayashi T, Mizutani M, Takikawa H, Sugimoto Y. 2-oxoglutarate-dependent dioxygenases and BAHD acyltransferases drive the structural diversification of orobanchol in Fabaceae plants. FRONTIERS IN PLANT SCIENCE 2024; 15:1392212. [PMID: 38699535 PMCID: PMC11063326 DOI: 10.3389/fpls.2024.1392212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 04/03/2024] [Indexed: 05/05/2024]
Abstract
Strigolactones (SLs), a class of plant apocarotenoids, serve dual roles as rhizosphere-signaling molecules and plant hormones. Orobanchol, a major naturally occurring SL, along with its various derivatives, has been detected in the root exudates of plants of the Fabaceae family. Medicaol, fabacyl acetate, and orobanchyl acetate were identified in the root exudates of barrel medic (Medicago truncatula), pea (Pisum sativum), and cowpea (Vigna unguiculata), respectively. Although the biosynthetic pathway leading to orobanchol production has been elucidated, the biosynthetic pathways of the orobanchol derivatives have not yet been fully elucidated. Here, we report the identification of 2-oxoglutarate-dependent dioxygenases (DOXs) and BAHD acyltransferases responsible for converting orobanchol to these derivatives in Fabaceae plants. First, the metabolic pathways downstream of orobanchol were analyzed using substrate feeding experiments. Prohexadione, an inhibitor of DOX inhibits the conversion of orobanchol to medicaol in barrel medic. The DOX inhibitor also reduced the formation of fabacyl acetate and fabacol, a precursor of fabacyl acetate, in pea. Subsequently, we utilized a dataset based on comparative transcriptome analysis to select a candidate gene encoding DOX for medicaol synthase in barrel medic. Recombinant proteins of the gene converted orobanchol to medicaol. The candidate genes encoding DOX and BAHD acyltransferase for fabacol synthase and fabacol acetyltransferase, respectively, were selected by co-expression analysis in pea. The recombinant proteins of the candidate genes converted orobanchol to fabacol and acetylated fabacol. Furthermore, fabacol acetyltransferase and its homolog in cowpea acetylated orobanchol. The kinetics and substrate specificity analyses revealed high affinity and strict recognition of the substrates of the identified enzymes. These findings shed light on the molecular mechanisms underlying the structural diversity of SLs.
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Affiliation(s)
- Masato Homma
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Japan
| | - Kiyono Uchida
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Takatoshi Wakabayashi
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Japan
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Masaharu Mizutani
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Japan
| | - Hirosato Takikawa
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Yukihiro Sugimoto
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Japan
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Nomura T, Seto Y, Kyozuka J. Unveiling the complexity of strigolactones: exploring structural diversity, biosynthesis pathways, and signaling mechanisms. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:1134-1147. [PMID: 37877933 DOI: 10.1093/jxb/erad412] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 10/20/2023] [Indexed: 10/26/2023]
Abstract
Strigolactone is the collective name for compounds containing a butenolide as a part of their structure, first discovered as compounds that induce seed germination of root parasitic plants. They were later found to be rhizosphere signaling molecules that induce hyphal branching of arbuscular mycorrhizal fungi, and, finally, they emerged as a class of plant hormones. Strigolactones are found in root exudates, where they display a great variability in their chemical structure. Their structure varies among plant species, and multiple strigolactones can exist in one species. Over 30 strigolactones have been identified, yet the chemical structure of the strigolactone that functions as an endogenous hormone and is found in the above-ground parts of plants remains unknown. We discuss our current knowledge of the synthetic pathways of diverse strigolactones and their regulation, as well as recent progress in identifying strigolactones as plant hormones. Strigolactone is perceived by the DWARF14 (D14), receptor, an α/β hydrolase which originated by gene duplication of KARRIKIN INSENSITIVE 2 (KAI2). D14 and KAI2 signaling pathways are partially overlapping paralogous pathways. Progress in understanding the signaling mechanisms mediated by two α/β hydrolase receptors as well as remaining challenges in the field of strigolactone research are reviewed.
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Affiliation(s)
- Takahito Nomura
- Center for Bioscience Research and Education, Utsunomiya University, Utsunomiya, Japan
| | - Yoshiya Seto
- School of Agriculture, Meiji University, Kawasaki, Japan
| | - Junko Kyozuka
- Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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Yamaguchi S, Seto Y, Kyozuka J. What's New in Strigolactone Research? PLANT & CELL PHYSIOLOGY 2023; 64:933-935. [PMID: 37655929 DOI: 10.1093/pcp/pcad095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 08/23/2023] [Accepted: 08/25/2023] [Indexed: 09/02/2023]
Affiliation(s)
- Shinjiro Yamaguchi
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
| | - Yoshiya Seto
- School of Agriculture, Meiji University, 1-1-1, Higashi-mita, Tama-ku, Kawasaki, 214-8571 Japan
| | - Junko Kyozuka
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577 Japan
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Dun EA, Brewer PB, Gillam EMJ, Beveridge CA. Strigolactones and Shoot Branching: What Is the Real Hormone and How Does It Work? PLANT & CELL PHYSIOLOGY 2023; 64:967-983. [PMID: 37526426 PMCID: PMC10504579 DOI: 10.1093/pcp/pcad088] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 07/26/2023] [Accepted: 08/01/2023] [Indexed: 08/02/2023]
Abstract
There have been substantial advances in our understanding of many aspects of strigolactone regulation of branching since the discovery of strigolactones as phytohormones. These include further insights into the network of phytohormones and other signals that regulate branching, as well as deep insights into strigolactone biosynthesis, metabolism, transport, perception and downstream signaling. In this review, we provide an update on recent advances in our understanding of how the strigolactone pathway co-ordinately and dynamically regulates bud outgrowth and pose some important outstanding questions that are yet to be resolved.
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Affiliation(s)
- Elizabeth A Dun
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, The University of Queensland, St Lucia, QLD 4072, Australia
- School of Agriculture and Food Sustainability, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Philip B Brewer
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, The University of Queensland, St Lucia, QLD 4072, Australia
- Waite Research Institute, School of Agriculture Food & Wine, The University of Adelaide, Adelaide, SA 5064, Australia
| | - Elizabeth M J Gillam
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Christine A Beveridge
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, The University of Queensland, St Lucia, QLD 4072, Australia
- School of Agriculture and Food Sustainability, The University of Queensland, St Lucia, QLD 4072, Australia
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Bajguz A, Piotrowska-Niczyporuk A. Biosynthetic Pathways of Hormones in Plants. Metabolites 2023; 13:884. [PMID: 37623827 PMCID: PMC10456939 DOI: 10.3390/metabo13080884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 07/22/2023] [Accepted: 07/24/2023] [Indexed: 08/26/2023] Open
Abstract
Phytohormones exhibit a wide range of chemical structures, though they primarily originate from three key metabolic precursors: amino acids, isoprenoids, and lipids. Specific amino acids, such as tryptophan, methionine, phenylalanine, and arginine, contribute to the production of various phytohormones, including auxins, melatonin, ethylene, salicylic acid, and polyamines. Isoprenoids are the foundation of five phytohormone categories: cytokinins, brassinosteroids, gibberellins, abscisic acid, and strigolactones. Furthermore, lipids, i.e., α-linolenic acid, function as a precursor for jasmonic acid. The biosynthesis routes of these different plant hormones are intricately complex. Understanding of these processes can greatly enhance our knowledge of how these hormones regulate plant growth, development, and physiology. This review focuses on detailing the biosynthetic pathways of phytohormones.
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Affiliation(s)
- Andrzej Bajguz
- Department of Biology and Plant Ecology, Faculty of Biology, University of Bialystok, Ciolkowskiego 1J, 15-245 Bialystok, Poland;
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