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Fu X, Yang H, Pangestu F, Nikolau BJ. Failure to Maintain Acetate Homeostasis by Acetate-Activating Enzymes Impacts Plant Development. PLANT PHYSIOLOGY 2020; 182:1256-1271. [PMID: 31874860 PMCID: PMC7054878 DOI: 10.1104/pp.19.01162] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 12/12/2019] [Indexed: 05/09/2023]
Abstract
The metabolic intermediate acetyl-CoA links anabolic and catabolic processes and coordinates metabolism with cellular signaling by influencing protein acetylation. In this study we demonstrate that in Arabidopsis (Arabidopsis thaliana), two distinctly localized acetate-activating enzymes, ACETYL-COA SYNTHETASE (ACS) in plastids and ACETATE NON-UTILIZING1 (ACN1) in peroxisomes, function redundantly to prevent the accumulation of excess acetate. In contrast to the near wild-type morphological and metabolic phenotypes of acs or acn1 mutants, the acs acn1 double mutant is delayed in growth and sterile, which is associated with hyperaccumulation of cellular acetate and decreased accumulation of acetyl-CoA-derived intermediates of central metabolism. Using multiple mutant stocks and stable isotope-assisted metabolic analyses, we demonstrate the twin metabolic origins of acetate from the oxidation of ethanol and the nonoxidative decarboxylation of pyruvate, with acetaldehyde being the common intermediate precursor of acetate. Conversion from pyruvate to acetate is activated under hypoxic conditions, and ACS recovers carbon that would otherwise be lost from the plant as ethanol. Plastid-localized ACS metabolizes cellular acetate and contributes to the de novo biosynthesis of fatty acids and Leu; peroxisome-localized ACN1 enables the incorporation of acetate into organic acids and amino acids. Thus, the activation of acetate in distinct subcellular compartments provides plants with the metabolic flexibility to maintain physiological levels of acetate and a metabolic mechanism for the recovery of carbon that would otherwise be lost as ethanol, for example following hypoxia.
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Affiliation(s)
- Xinyu Fu
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011
- Center for Biorenewable Chemicals (CBiRC), Iowa State University, Ames, Iowa 50011
- Center for Metabolic Biology, Iowa State University, Ames, Iowa 50011
| | - Hannah Yang
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011
| | - Febriana Pangestu
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011
| | - Basil J Nikolau
- Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, Iowa 50011
- Center for Biorenewable Chemicals (CBiRC), Iowa State University, Ames, Iowa 50011
- Center for Metabolic Biology, Iowa State University, Ames, Iowa 50011
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2
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Pan R, Liu J, Wang S, Hu J. Peroxisomes: versatile organelles with diverse roles in plants. THE NEW PHYTOLOGIST 2020; 225:1410-1427. [PMID: 31442305 DOI: 10.1111/nph.16134] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 08/08/2019] [Indexed: 05/18/2023]
Abstract
Peroxisomes are small, ubiquitous organelles that are delimited by a single membrane and lack genetic material. However, these simple-structured organelles are highly versatile in morphology, abundance and protein content in response to various developmental and environmental cues. In plants, peroxisomes are essential for growth and development and perform diverse metabolic functions, many of which are carried out coordinately by peroxisomes and other organelles physically interacting with peroxisomes. Recent studies have added greatly to our knowledge of peroxisomes, addressing areas such as the diverse proteome, regulation of division and protein import, pexophagy, matrix protein degradation, solute transport, signaling, redox homeostasis and various metabolic and physiological functions. This review summarizes our current understanding of plant peroxisomes, focusing on recent discoveries. Current problems and future efforts required to better understand these organelles are also discussed. An improved understanding of peroxisomes will be important not only to the understanding of eukaryotic cell biology and metabolism, but also to agricultural efforts aimed at improving crop performance and defense.
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Affiliation(s)
- Ronghui Pan
- Seed Science Center, Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Jun Liu
- Seed Science Center, Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Saisai Wang
- Seed Science Center, Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Jianping Hu
- MSU-Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Plant Biology Department, Michigan State University, East Lansing, MI, 48824, USA
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3
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Aryal B, Huynh J, Schneuwly J, Siffert A, Liu J, Alejandro S, Ludwig-Müller J, Martinoia E, Geisler M. ABCG36/PEN3/PDR8 Is an Exporter of the Auxin Precursor, Indole-3-Butyric Acid, and Involved in Auxin-Controlled Development. FRONTIERS IN PLANT SCIENCE 2019; 10:899. [PMID: 31354769 PMCID: PMC6629959 DOI: 10.3389/fpls.2019.00899] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 06/25/2019] [Indexed: 05/18/2023]
Abstract
The PDR-type ABCG transporter, ABCG36/PDR8/PEN3, is thought to be implicated in the export of a few structurally unrelated substrates, including the auxin precursor, indole-3-butyric acid (IBA), although a clear-cut proof of transport is lacking. An outward facing, lateral root (LR) location for ABCG36 fuelled speculations that it might secrete IBA into the rhizosphere. Here, we provide strong evidence that ABCG36 catalyzes the export of IBA - but not of indole-3-acetic acid - through the plasma membrane. ABCG36 seems to function redundantly with the closely related isoform ABCG37/PDR9/PIS1 in a negative control of rootward IBA transport in roots, which might be dampened by concerted, lateral IBA export. Analyses of single and double mutant phenotypes suggest that both ABCG36 and ABCG37 function cooperatively in auxin-controlled plant development. Both seem to possess a dual function in the control of auxin homeostasis in the root tip and long-range transport in the mature root correlating with non-polar and polar expression profiles in the LR cap and epidermis, respectively.
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Affiliation(s)
- Bibek Aryal
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - John Huynh
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Jerôme Schneuwly
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Alexandra Siffert
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Jie Liu
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | | | | | | | - Markus Geisler
- Department of Biology, University of Fribourg, Fribourg, Switzerland
- *Correspondence: Markus Geisler,
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4
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Lefèvre F, Boutry M. Towards Identification of the Substrates of ATP-Binding Cassette Transporters. PLANT PHYSIOLOGY 2018; 178:18-39. [PMID: 29987003 PMCID: PMC6130012 DOI: 10.1104/pp.18.00325] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 06/08/2018] [Indexed: 05/05/2023]
Abstract
Most ATP-binding cassette (ABC) proteins function in transmembrane transport, and plant genomes encode a large number of ABC transporters compared with animal or fungal genomes. These transporters have been classified into eight subfamilies according to their topology and phylogenetic relationships. Transgenic plants and mutants with altered ABC transporter expression or function have contributed to deciphering the physiological roles of these proteins, such as in plant development, responses to biotic and abiotic stress, or detoxification activities within the cell. In agreement with the diversity of these functions, a large range of substrates (e.g. hormones and primary and secondary metabolites) have been identified. We review in detail transporters for which substrates have been unambiguously identified. However, some cases are far from clear, because some ABC transporters have the ability to transport several structurally unrelated substrates or because the identification of their substrates was performed indirectly without any flux measurement. Various heterologous or homologous expression systems have been used to better characterize the transport activity and other biochemical properties of ABC transporters, opening the way to addressing new issues such as the particular structural features of plant ABC transporters, the bidirectionality of transport, or the role of posttranslational modifications.
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Affiliation(s)
- François Lefèvre
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, 1348 Louvain-la-Neuve, Belgium
| | - Marc Boutry
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, 1348 Louvain-la-Neuve, Belgium
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5
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Park J, Lee Y, Martinoia E, Geisler M. Plant hormone transporters: what we know and what we would like to know. BMC Biol 2017; 15:93. [PMID: 29070024 PMCID: PMC5655956 DOI: 10.1186/s12915-017-0443-x] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Hormone transporters are crucial for plant hormone action, which is underlined by severe developmental and physiological impacts caused by their loss-of-function mutations. Here, we summarize recent knowledge on the individual roles of plant hormone transporters in local and long-distance transport. Our inventory reveals that many hormones are transported by members of distinct transporter classes, with an apparent dominance of the ATP-binding cassette (ABC) family and of the Nitrate transport1/Peptide transporter family (NPF). The current need to explore further hormone transporter regulation, their functional interaction, transport directionalities, and substrate specificities is briefly reviewed.
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Affiliation(s)
- Jiyoung Park
- Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0116, USA.
| | - Youngsook Lee
- Division of Integrative Bioscience and Biotechnology, POSTECH, Pohang, 37673, South Korea
| | - Enrico Martinoia
- Institute for Plant Biology, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland
| | - Markus Geisler
- Department of Biology, University of Fribourg, 1700, Fribourg, Switzerland.
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Geisler M, Aryal B, di Donato M, Hao P. A Critical View on ABC Transporters and Their Interacting Partners in Auxin Transport. PLANT & CELL PHYSIOLOGY 2017; 58:1601-1614. [PMID: 29016918 DOI: 10.1093/pcp/pcx104] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 07/18/2017] [Indexed: 05/24/2023]
Abstract
Different subclasses of ATP-binding cassette (ABC) transporters have been implicated in the transport of native variants of the phytohormone auxin. Here, the putative, individual roles of key members belonging to the ABCB, ABCD and ABCG families, respectively, are highlighted and the knowledge of their assumed expression and transport routes is reviewed and compared with their mutant phenotypes. Protein-protein interactions between ABC transporters and regulatory components during auxin transport are summarized and their importance is critically discussed. There is a focus on the functional interaction between members of the ABCB family and the FKBP42, TWISTED DWARF1, acting as a chaperone during plasma membrane trafficking of ABCBs. Further, the mode and relevance of functional ABCB-PIN interactions is diagnostically re-evaluated. A new nomenclature describing precisely the most likely ABCB-PIN interaction scenarios is suggested. Finally, available tools for the detection and prediction of ABC transporter interactomes are summarized and the potential of future ABC transporter interactome maps is highlighted.
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Affiliation(s)
- Markus Geisler
- University of Fribourg, Department of Biology, CH-1700 Fribourg, Switzerland
| | - Bibek Aryal
- University of Fribourg, Department of Biology, CH-1700 Fribourg, Switzerland
| | - Martin di Donato
- University of Fribourg, Department of Biology, CH-1700 Fribourg, Switzerland
| | - Pengchao Hao
- University of Fribourg, Department of Biology, CH-1700 Fribourg, Switzerland
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7
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How to move an amphipathic molecule across a lipid bilayer: different mechanisms for different ABC transporters? Biochem Soc Trans 2017; 44:774-82. [PMID: 27284041 PMCID: PMC4900756 DOI: 10.1042/bst20160040] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Indexed: 02/06/2023]
Abstract
Import of β-oxidation substrates into peroxisomes is mediated by ATP binding cassette (ABC) transporters belonging to subfamily D. In order to enter the β-oxidation pathway, fatty acids are activated by conversion to fatty acyl-CoA esters, a reaction which is catalysed by acyl-CoA synthetases (ACSs). Here, we present evidence for an unusual transport mechanism, in which fatty acyl-CoA substrates are accepted by ABC subclass D protein (ABCD) transporters, cleaved by the transporters during transit across the lipid bilayer to release CoA, and ultimately re-esterified in the peroxisome lumen by ACSs which interact with the transporter. We propose that this solves the biophysical problem of moving an amphipathic molecule across the peroxisomal membrane, since the intrinsic thioesterase activity of the transporter permits separate membrane translocation pathways for the hydrophobic fatty acid moiety and the polar CoA moiety. The cleavage/re-esterification mechanism also has the potential to control entry of disparate substrates into the β-oxidation pathway when coupled with distinct peroxisomal ACSs. A different solution to the movement of amphipathic molecules across a lipid bilayer is deployed by the bacterial lipid-linked oligosaccharide (LLO) flippase, PglK, in which the hydrophilic head group and the hydrophobic polyprenyl tail of the substrate are proposed to have distinct translocation pathways but are not chemically separated during transport. We discuss a speculative alternating access model for ABCD proteins based on the mammalian ABC transporter associated with antigen processing (TAP) and compare it to the novel mechanism suggested by the recent PglK crystal structures and biochemical data.
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Li N, Xu C, Li-Beisson Y, Philippar K. Fatty Acid and Lipid Transport in Plant Cells. TRENDS IN PLANT SCIENCE 2016; 21:145-158. [PMID: 26616197 DOI: 10.1016/j.tplants.2015.10.011] [Citation(s) in RCA: 150] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 09/29/2015] [Accepted: 10/15/2015] [Indexed: 05/18/2023]
Abstract
Fatty acids (FAs) and lipids are essential - not only as membrane constituents but also for growth and development. In plants and algae, FAs are synthesized in plastids and to a large extent transported to the endoplasmic reticulum for modification and lipid assembly. Subsequently, lipophilic compounds are distributed within the cell, and thus are transported across most membrane systems. Membrane-intrinsic transporters and proteins for cellular FA/lipid transfer therefore represent key components for delivery and dissemination. In addition to highlighting their role in lipid homeostasis and plant performance, different transport mechanisms for land plants and green algae - in the model systems Arabidopsis thaliana, Chlamydomonas reinhardtii - are compared, thereby providing a current perspective on protein-mediated FA and lipid trafficking in photosynthetic cells.
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Affiliation(s)
- Nannan Li
- Research Center of Bioenergy and Bioremediation (RCBB), College of Resources and Environment, Southwest University, Beibei District, Chongqing, 400715, P.R. China
| | - Changcheng Xu
- Biology Department, Brookhaven National Laboratory, 50 Bell Avenue, Upton, NY 11973-5000, USA
| | - Yonghua Li-Beisson
- Institute of Environmental Biology and Biotechnology, The French Atomic and Alternative Energy Commission, Unité Mixte de Recherche 7265, Commissariat à l'Energie Atomique (CEA) Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - Katrin Philippar
- Department of Biology I, Ludwig-Maximilians-University München, 82152 Planegg-Martinsried, Germany.
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9
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Abstract
Peroxisomes are arguably the most biochemically versatile of all eukaryotic organelles. Their metabolic functions vary between different organisms, between different tissue types of the same organism and even between different developmental stages or in response to changed environmental conditions. New functions for peroxisomes are still being discovered and their importance is underscored by the severe phenotypes that can arise as a result of peroxisome dysfunction. The β-oxidation pathway is central to peroxisomal metabolism, but the substrates processed are very diverse, reflecting the diversity of peroxisomes across species. Substrates for β-oxidation enter peroxisomes via ATP-binding cassette (ABC) transporters of subfamily D; (ABCD) and are activated by specific acyl CoA synthetases for further metabolism. Humans have three peroxisomal ABCD family members, which are half transporters that homodimerize and have distinct but partially overlapping substrate specificity; Saccharomyces cerevisiae has two half transporters that heterodimerize and plants have a single peroxisomal ABC transporter that is a fused heterodimer and which appears to be the single entry point into peroxisomes for a very wide variety of β-oxidation substrates. Our studies suggest that the Arabidopsis peroxisomal ABC transporter AtABCD1 accepts acyl CoA substrates, cleaves them before or during transport followed by reactivation by peroxisomal synthetases. We propose that this is a general mechanism to provide specificity to this class of transporters and by which amphipathic compounds are moved across peroxisome membranes.
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10
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Andolfo G, Ruocco M, Di Donato A, Frusciante L, Lorito M, Scala F, Ercolano MR. Genetic variability and evolutionary diversification of membrane ABC transporters in plants. BMC PLANT BIOLOGY 2015; 15:51. [PMID: 25850033 PMCID: PMC4358917 DOI: 10.1186/s12870-014-0323-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 11/06/2014] [Indexed: 05/18/2023]
Abstract
BACKGROUND ATP-binding cassette proteins have been recognized as playing a crucial role in the regulation of growth and resistance processes in all kingdoms of life. They have been deeply studied in vertebrates because of their role in drug resistance, but much less is known about ABC superfamily functions in plants. RESULTS Recently released plant genome sequences allowed us to identify 803 ABC transporters in four vascular plants (Oryza. sativa, Solanum lycopersicum, Solanum tuberosum and Vitis vinifera) and 76 transporters in the green alga Volvox carteri, by comparing them with those reannotated in Arabidopsis thaliana and the yeast Saccharomyces cerevisiae. Retrieved proteins have been phylogenetically analysed to infer orthologous relationships. Most orthologous relationships in the A, D, E and F subfamilies were found, and interesting expansions within the ABCG subfamily were observed and discussed. A high level of purifying selection is acting in the five ABC subfamilies A, B, C, D and E. However, evolutionary rates of recent duplicate genes could influence vascular plant genome diversification. The transcription profiles of ABC genes within tomato organs revealed a broad functional role for some transporters and a more specific activity for others, suggesting the presence of key ABC regulators in tomato. CONCLUSIONS The findings achieved in this work could contribute to address several biological questions concerning the evolution of the relationship between genomes of different species. Plant ABC protein inventories obtained could be a valuable tool both for basic and applied studies. Indeed, interpolation of the putative role of gene functions can accelerate the discovering of new ABC superfamily members.
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Affiliation(s)
- Giuseppe Andolfo
- />Department of Agricultural Sciences, University of Naples ‘Federico II’, Via Universita’ 100, 80055 Portici, Italy
| | - Michelina Ruocco
- />CNR – Istituto per la Protezione Sostenibile delle Piante (IPSP-CNR), Portici, Italy
| | - Antimo Di Donato
- />Department of Agricultural Sciences, University of Naples ‘Federico II’, Via Universita’ 100, 80055 Portici, Italy
| | - Luigi Frusciante
- />Department of Agricultural Sciences, University of Naples ‘Federico II’, Via Universita’ 100, 80055 Portici, Italy
| | - Matteo Lorito
- />Department of Agricultural Sciences, University of Naples ‘Federico II’, Via Universita’ 100, 80055 Portici, Italy
| | - Felice Scala
- />Department of Agricultural Sciences, University of Naples ‘Federico II’, Via Universita’ 100, 80055 Portici, Italy
| | - Maria Raffaella Ercolano
- />Department of Agricultural Sciences, University of Naples ‘Federico II’, Via Universita’ 100, 80055 Portici, Italy
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11
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Selective induction and subcellular distribution of ACONITASE 3 reveal the importance of cytosolic citrate metabolism during lipid mobilization in Arabidopsis. Biochem J 2014; 463:309-17. [PMID: 25061985 DOI: 10.1042/bj20140430] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Arabidopsis thaliana has three genes that encode distinct aconitases (ACO), but little is known about the function of each isoenzyme during plant development. In newly emerged seedlings of Arabidopsis, transcript and protein levels for ACO3 were selectively induced to yield more than 80% of total aconitase activity. Characterization of knockout mutants for each of the three ACOs suggests a major role for only ACO3 in citrate metabolism. The aco3 mutant showed delayed early seedling growth, altered assimilation of [14C]acetate feeding and elevated citrate levels, which were nearly 4-fold greater than in wild-type, aco1 or aco2. However, both ACO1 and ACO2 are active in seedlings as shown by inhibition of aco3 growth by the toxin monofluoroacetate, and altered [14C]acetate assimilation and metabolite levels in aco1 and aco2. Relative levels of fumarate and malate differed between aco2 and aco3, indicating metabolically isolated pools of these metabolites in seedlings. Our inability to enrich ACO protein through mitochondria isolation, and the reduced cytosolic ACO activity of the iron-sulfur centre assembly mutant atm3-1, indicated a cytosolic localization of ACO3 in 3-day-old seedlings. Subsequently, we determined that more than 90% of ACO3 was cytosolic. We conclude that ACO3 is cytosolic in young seedlings and functions in citrate catabolism consistent with the operation of the classic glyoxylate and not direct catabolism of citrate within mitochondria.
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12
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Mendiondo GM, Medhurst A, van Roermund CW, Zhang X, Devonshire J, Scholefield D, Fernández J, Axcell B, Ramsay L, Waterham HR, Waugh R, Theodoulou FL, Holdsworth MJ. Barley has two peroxisomal ABC transporters with multiple functions in β-oxidation. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:4833-47. [PMID: 24913629 PMCID: PMC4144768 DOI: 10.1093/jxb/eru243] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In oilseed plants, peroxisomal β-oxidation functions not only in lipid catabolism but also in jasmonate biosynthesis and metabolism of pro-auxins. Subfamily D ATP-binding cassette (ABC) transporters mediate import of β-oxidation substrates into the peroxisome, and the Arabidopsis ABCD protein, COMATOSE (CTS), is essential for this function. Here, the roles of peroxisomal ABCD transporters were investigated in barley, where the main storage compound is starch. Barley has two CTS homologues, designated HvABCD1 and HvABCD2, which are widely expressed and present in embryo and aleurone tissues during germination. Suppression of both genes in barley RNA interference (RNAi) lines indicated roles in metabolism of 2,4-dichlorophenoxybutyrate (2,4-DB) and indole butyric acid (IBA), jasmonate biosynthesis, and determination of grain size. Transformation of the Arabidopsis cts-1 null mutant with HvABCD1 and HvABCD2 confirmed these findings. HvABCD2 partially or completely complemented all tested phenotypes of cts-1. In contrast, HvABCD1 failed to complement the germination and establishment phenotypes of cts-1 but increased the sensitivity of hypocotyls to 100 μM IBA and partially complemented the seed size phenotype. HvABCD1 also partially complemented the yeast pxa1/pxa2Δ mutant for fatty acid β-oxidation. It is concluded that the core biochemical functions of peroxisomal ABC transporters are largely conserved between oilseeds and cereals but that their physiological roles and importance may differ.
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Affiliation(s)
- Guillermina M Mendiondo
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Anne Medhurst
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Carlo W van Roermund
- Laboratory of Genetic Metabolic Diseases, Academic Medical Centre, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands
| | - Xuebin Zhang
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden AL5 2JQ, UK
| | - Jean Devonshire
- Plant Biology and Crop Science Department, Rothamsted Research, Harpenden AL5 2JQ, UK
| | - Duncan Scholefield
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - José Fernández
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Barry Axcell
- SABMiller plc., SABMiller House, Church Street, West Woking, Surrey GU21 6HS, UK
| | - Luke Ramsay
- Division of Plant Sciences, College of life Sciences, University of Dundee and The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Hans R Waterham
- Laboratory of Genetic Metabolic Diseases, Academic Medical Centre, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands
| | - Robbie Waugh
- Division of Plant Sciences, College of life Sciences, University of Dundee and The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Frederica L Theodoulou
- Biological Chemistry and Crop Protection Department, Rothamsted Research, Harpenden AL5 2JQ, UK
| | - Michael J Holdsworth
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
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13
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Kassmann CM. Myelin peroxisomes - essential organelles for the maintenance of white matter in the nervous system. Biochimie 2013; 98:111-8. [PMID: 24120688 DOI: 10.1016/j.biochi.2013.09.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Accepted: 09/20/2013] [Indexed: 12/29/2022]
Abstract
Peroxisomes are cellular compartments primarily associated with lipid metabolism. Most cell types, including nervous system cells, harbor several hundred of these organelles. The importance of peroxisomes for central nervous system white matter is evidenced by a variety of human peroxisomal disorders with neurological impairment frequently involving the white matter. Moreover, the most frequent childhood white matter disease, X-linked adrenoleukodystrophy, is a peroxisomal disorder. During the past decade advances in imaging techniques have enabled the identification of peroxisomes within the myelin sheath, especially close to nodes of Ranvier. Although the function of myelin peroxisomes is not solved yet on molecular level, recently acquired knowledge suggests a central role for these organelles in axo-glial metabolism. This review focuses on the biology of myelin peroxisomes as well as on the pathology of myelin and myelinated axons that is observed as a consequence of partial or complete peroxisomal dysfunction in the brain.
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Affiliation(s)
- Celia M Kassmann
- Department of Neurogenetics, Max Planck Institute of Experimental Medicine, Hermann-Rein-Straße 3, 37075 Göttingen, Germany.
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14
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Kunze M, Hartig A. Permeability of the peroxisomal membrane: lessons from the glyoxylate cycle. Front Physiol 2013; 4:204. [PMID: 23966945 PMCID: PMC3743077 DOI: 10.3389/fphys.2013.00204] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Accepted: 07/19/2013] [Indexed: 01/09/2023] Open
Abstract
Glyoxylate serves as intermediate in various metabolic pathways, although high concentrations of this metabolite are toxic to the cell. In many organisms glyoxylate is fed into the glyoxylate cycle. Enzymes participating in this metabolism are located on both sides of the peroxisomal membrane. The permeability of this membrane for small metabolites paves the way for exchange of intermediates between proteins catalyzing consecutive reactions. A model, in which soluble enzymes accumulate in close proximity to both ends of pore-like structures forming a transmembrane metabolon could explain the rapid and targeted exchange of intermediates. The metabolites passing the membrane differ between the three model organisms Saccharomyces cerevisiae, Arabidopsis thaliana, and Candida albicans, which reflects the ease of evolutionary adaptation processes whenever specific transporter proteins are not involved. The atypical permeability properties of the peroxisomal membrane together with a flexible structural arrangement ensuring the swift and selective transport across the membrane might represent the molecular basis for the functional versatility of peroxisomes.
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Affiliation(s)
- Markus Kunze
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna Vienna, Austria
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15
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Inventory and general analysis of the ATP-binding cassette (ABC) gene superfamily in maize (Zea mays L.). Gene 2013; 526:411-28. [PMID: 23747399 DOI: 10.1016/j.gene.2013.05.051] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 05/24/2013] [Accepted: 05/27/2013] [Indexed: 12/28/2022]
Abstract
The metabolic functions of ATP-binding cassette (or ABC) proteins, one of the largest families of proteins presented in all organisms, have been investigated in many protozoan, animal and plant species. To facilitate more systematic and complicated studies on maize ABC proteins in the future, we present the first complete inventory of these proteins, including 130 open reading frames (ORFs), and provide general descriptions of their classifications, basic structures, typical functions, evolution track analysis and expression profiles. The 130 ORFs were assigned to eight subfamilies based on their structures and homological features. Five of these subfamilies consist of 109 proteins, containing transmembrane domains (TM) performing as transporters. The rest three subfamilies contain 21 soluble proteins involved in various functions other than molecular transport. A comparison of ABC proteins among nine selected species revealed either convergence or divergence in each of the ABC subfamilies. Generally, plant genomes contain far more ABC genes than animal genomes. The expression profiles and evolution track of each maize ABC gene were further investigated, the results of which could provide clues for analyzing their functions. Quantitative real-time polymerase chain reaction experiments (PCR) were conducted to detect induced expression in select ABC genes under several common stresses. This investigation provides valuable information for future research on stress tolerance in plants and potential strategies for enhancing maize production under stressful conditions.
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16
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van Roermund CWT, Ijlst L, Majczak W, Waterham HR, Folkerts H, Wanders RJA, Hellingwerf KJ. Peroxisomal fatty acid uptake mechanism in Saccharomyces cerevisiae. J Biol Chem 2012; 287:20144-53. [PMID: 22493507 DOI: 10.1074/jbc.m111.332833] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Peroxisomes play a major role in human cellular lipid metabolism, including fatty acid β-oxidation. The most frequent peroxisomal disorder is X-linked adrenoleukodystrophy, which is caused by mutations in ABCD1. The biochemical hallmark of X-linked adrenoleukodystrophy is the accumulation of very long chain fatty acids (VLCFAs) due to impaired peroxisomal β-oxidation. Although this suggests a role of ABCD1 in VLCFA import into peroxisomes, no direct experimental evidence is available to substantiate this. To unravel the mechanism of peroxisomal VLCFA transport, we use Saccharomyces cerevisiae as a model organism. Here we provide evidence that in this organism very long chain acyl-CoA esters are hydrolyzed by the Pxa1p-Pxa2p complex prior to the actual transport of their fatty acid moiety into the peroxisomes with the CoA presumably being released into the cytoplasm. The Pxa1p-Pxa2p complex functionally interacts with the acyl-CoA synthetases Faa2p and/or Fat1p on the inner surface of the peroxisomal membrane for subsequent re-esterification of the VLCFAs. Importantly, the Pxa1p-Pxa2p complex shares this molecular mechanism with HsABCD1 and HsABCD2.
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Affiliation(s)
- Carlo W T van Roermund
- Departments of Pediatrics and Clinical Chemistry, Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
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17
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Khan BR, Adham AR, Zolman BK. Peroxisomal Acyl-CoA oxidase 4 activity differs between Arabidopsis accessions. PLANT MOLECULAR BIOLOGY 2012; 78:45-58. [PMID: 22048901 DOI: 10.1007/s11103-011-9843-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 10/20/2011] [Indexed: 05/24/2023]
Abstract
In plants, peroxisomes are the primary site of fatty acid β-oxidation. Following substrate activation, fatty acids are oxidized by Acyl-CoA Oxidase (ACX) enzymes. Arabidopsis has six ACX genes, although ACX6 is not expressed. Biochemical characterization has revealed that each ACX enzyme acts on specific chain-length targets, but in a partially overlapping manner, indicating a degree of functional redundancy. Genetic analysis of acx single and double mutants in the Columbia (Col-0) accession revealed only minor phenotypes, but an acx3acx4 double mutant from Wassileskija (Ws) is embryo lethal. In this study, we show that acx3acx4(Col) and acx1acx3acx4(Col) mutants are viable and that enzyme activity in these mutants is significantly reduced on a range of substrates compared to wild type. However, the triple mutant displays only minor defects in seed-storage mobilization, seedling development, and adult growth. Although the triple mutant is defective in the three most active and highly-expressed ACX proteins, increases in ACX2 expression may support partial β-oxidation activity. Comparison of acx mutant alleles in the Col-0 and Ws accessions reveals independent phenotypes; the Ws acx4 mutant uniquely shows increased sensitivity to propionate, whereas the Col-0 acx4 allele has sucrose-dependent growth in the light. To dissect the issues between Col-0 and Ws, we generated mixed background mutants. Although alleles with the Col-0 acx4 mutant were viable, we were unable to isolate an acx3acx4 line using the Ws acx4 allele. Reducing ACX4 expression in several Arabidopsis backgrounds showed a split response, suggesting that the ACX4 gene and/or protein functions differently in Arabidopsis accessions.
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Affiliation(s)
- Bibi Rafeiza Khan
- Department of Biology, University of Missouri, St. Louis, St. Louis, MO 63121, USA
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18
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Kang J, Park J, Choi H, Burla B, Kretzschmar T, Lee Y, Martinoia E. Plant ABC Transporters. THE ARABIDOPSIS BOOK 2011; 9:e0153. [PMID: 22303277 PMCID: PMC3268509 DOI: 10.1199/tab.0153] [Citation(s) in RCA: 282] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
ABC transporters constitute one of the largest protein families found in all living organisms. ABC transporters are driven by ATP hydrolysis and can act as exporters as well as importers. The plant genome encodes for more than 100 ABC transporters, largely exceeding that of other organisms. In Arabidopsis, only 22 out of 130 have been functionally analyzed. They are localized in most membranes of a plant cell such as the plasma membrane, the tonoplast, chloroplasts, mitochondria and peroxisomes and fulfill a multitude of functions. Originally identified as transporters involved in detoxification processes, they have later been shown to be required for organ growth, plant nutrition, plant development, response to abiotic stresses, pathogen resistance and the interaction of the plant with its environment. To fulfill these roles they exhibit different substrate specifies by e.g. depositing surface lipids, accumulating phytate in seeds, and transporting the phytohormones auxin and abscisic acid. The aim of this review is to give an insight into the functions of plant ABC transporters and to show their importance for plant development and survival.
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Affiliation(s)
- Joohyun Kang
- POSTECH-UZH Global Research Laboratory, Division of Molecular Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Jiyoung Park
- POSTECH-UZH Global Research Laboratory, Division of Molecular Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Hyunju Choi
- POSTECH-UZH Global Research Laboratory, Division of Molecular Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Bo Burla
- Institute of Plant Biology, University Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland
| | - Tobias Kretzschmar
- Institute of Plant Biology, University Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland
| | - Youngsook Lee
- POSTECH-UZH Global Research Laboratory, Division of Molecular Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
- Division of Integrative Biosciences and Biotechnology, World Class University Program, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Enrico Martinoia
- POSTECH-UZH Global Research Laboratory, Division of Molecular Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
- Institute of Plant Biology, University Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland
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19
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Tilbrook K, Gebbie L, Schenk PM, Poirier Y, Brumbley SM. Peroxisomal polyhydroxyalkanoate biosynthesis is a promising strategy for bioplastic production in high biomass crops. PLANT BIOTECHNOLOGY JOURNAL 2011; 9:958-969. [PMID: 21447054 DOI: 10.1111/j.1467-7652.2011.00600.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Polyhydroxyalkanoates (PHAs) are bacterial carbon storage polymers with diverse plastic-like properties. PHA biosynthesis in transgenic plants is being developed as a way to reduce the cost and increase the sustainability of industrial PHA production. The homopolymer polyhydroxybutyrate (PHB) is the simplest form of these biodegradable polyesters. Plant peroxisomes contain the substrate molecules and necessary reducing power for PHB biosynthesis, but peroxisomal PHB production has not been explored in whole soil-grown transgenic plants to date. We generated transgenic sugarcane (Saccharum sp.) with the three-enzyme Ralstonia eutropha PHA biosynthetic pathway targeted to peroxisomes. We also introduced the pathway into Arabidopsis thaliana, as a model system for studying and manipulating peroxisomal PHB production. PHB, at levels up to 1.6%-1.8% dry weight, accumulated in sugarcane leaves and A. thaliana seedlings, respectively. In sugarcane, PHB accumulated throughout most leaf cell types in both peroxisomes and vacuoles. A small percentage of total polymer was also identified as the copolymer poly (3-hydroxybutyrate-co-3-hydroxyvalerate) in both plant species. No obvious deleterious effect was observed on plant growth because of peroxisomal PHA biosynthesis at these levels. This study highlights how using peroxisomal metabolism for PHA biosynthesis could significantly contribute to reaching commercial production levels of PHAs in crop plants.
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Affiliation(s)
- Kimberley Tilbrook
- The University of Queensland, School of Biological Science, Brisbane, Qld, Australia
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20
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Evidence that ACN1 (acetate non-utilizing 1) prevents carbon leakage from peroxisomes during lipid mobilization in Arabidopsis seedlings. Biochem J 2011; 437:505-13. [DOI: 10.1042/bj20101764] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
ACN1 (acetate non-utilizing 1) is a short-chain acyl-CoA synthetase which recycles free acetate to acetyl-CoA in peroxisomes of Arabidopsis. Pulse-chase [2-13C]acetate feeding of the mutant acn1–2 revealed that acetate accumulation and assimilation were no different to that of wild-type, Col-7. However, the lack of acn1–2 led to a decrease of nearly 50% in 13C-labelling of glutamine, a major carbon sink in seedlings, and large decreases in primary metabolite levels. In contrast, acetyl-CoA levels were higher in acn1–2 compared with Col-7. The disappearance of eicosenoic acid was slightly delayed in acn1–2 indicating only a small effect on the rate of lipid breakdown. A comparison of transcript levels in acn1–2 and Col-7 showed that induced genes included a number of metabolic genes and also a large number of signalling-related genes. Genes repressed in the mutant were represented primarily by embryogenesis-related genes. Transcript levels of glyoxylate cycle genes also were lower in acn1–2 than in Col-7. We conclude that deficiency in peroxisomal acetate assimilation comprises only a small proportion of total acetate use, but this affects both primary metabolism and gene expression. We discuss the possibility that ACN1 safeguards against the loss of carbon as acetate from peroxisomes during lipid mobilization.
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21
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Zhang X, De Marcos Lousa C, Schutte-Lensink N, Ofman R, Wanders RJ, Baldwin SA, Baker A, Kemp S, Theodoulou FL. Conservation of targeting but divergence in function and quality control of peroxisomal ABC transporters: an analysis using cross-kingdom expression. Biochem J 2011; 436:547-57. [PMID: 21476988 DOI: 10.1042/bj20110249] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
ABC (ATP-binding cassette) subfamily D transporters are found in all eukaryotic kingdoms and are known to play essential roles in mammals and plants; however, their number, organization and physiological contexts differ. Via cross-kingdom expression experiments, we have explored the conservation of targeting, protein stability and function between mammalian and plant ABCD transporters. When expressed in tobacco epidermal cells, the mammalian ABCD proteins ALDP (adrenoleukodystrophy protein), ALDR (adrenoleukodystrophy-related protein) and PMP70 (70 kDa peroxisomal membrane protein) targeted faithfully to peroxisomes and P70R (PMP70-related protein) targeted to the ER (endoplasmic reticulum), as in the native host. The Arabidopsis thaliana peroxin AtPex19_1 interacted with human peroxisomal ABC transporters both in vivo and in vitro, providing an explanation for the fidelity of targeting. The fate of X-linked adrenoleukodystrophy disease-related mutants differed between fibroblasts and plant cells. In fibroblasts, levels of ALDP in some 'protein-absent' mutants were increased by low-temperature culture, in some cases restoring function. In contrast, all mutant ALDP proteins examined were stable and correctly targeted in plant cells, regardless of their fate in fibroblasts. ALDR complemented the seed germination defect of the Arabidopsis cts-1 mutant which lacks the peroxisomal ABCD transporter CTS (Comatose), but neither ALDR nor ALDP was able to rescue the defect in fatty acid β-oxidation in establishing seedlings. Taken together, our results indicate that the mechanism for trafficking of peroxisomal membrane proteins is shared between plants and mammals, but suggest differences in the sensing and turnover of mutant ABC transporter proteins and differences in substrate specificity and/or function.
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Affiliation(s)
- Xuebin Zhang
- Biological Chemistry Department, Rothamsted Research, Harpenden, Herts. AL5 2JQ, UK
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22
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Modelling the peroxisomal carbon leak during lipid mobilization in Arabidopsis. Biochem Soc Trans 2011; 38:1230-3. [PMID: 20863290 DOI: 10.1042/bst0381230] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mutation of the ACN1 (acetate non-utilizing 1) locus of Arabidopsis results in altered acetate assimilation into gluconeogenic sugars and anapleurotic amino acids and leads to an overall depression in primary metabolite levels by approx. 50% during seedling development. Levels of acetyl-CoA were higher in acn1 compared with wild-type, which is counterintuitive to the activity of ACN1 as a peroxisomal acetyl-CoA synthetase. We hypothesize that ACN1 recycles free acetate to acetyl-CoA within peroxisomes in order that carbon remains fed into the glyoxylate cycle. When ACN1 is not present, carbon in the form of acetate can leak out of peroxisomes and is reactivated to acetyl-CoA within the cytosol. Kinetic models incorporating estimates of carbon input and pathway dynamics from a variety of literature sources have proven useful in explaining how ACN1 may prevent the carbon leak and even contribute to the control of peroxisomal carbon metabolism.
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23
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Kaur N, Hu J. Defining the plant peroxisomal proteome: from Arabidopsis to rice. FRONTIERS IN PLANT SCIENCE 2011; 2:103. [PMID: 22645559 PMCID: PMC3355810 DOI: 10.3389/fpls.2011.00103] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 12/08/2011] [Indexed: 05/08/2023]
Abstract
Peroxisomes are small subcellular organelles mediating a multitude of processes in plants. Proteomics studies over the last several years have yielded much needed information on the composition of plant peroxisomes. In this review, the status of peroxisome proteomics studies in Arabidopsis and other plant species and the cumulative advances made through these studies are summarized. A reference Arabidopsis peroxisome proteome is generated, and some unique aspects of Arabidopsis peroxisomes that were uncovered through proteomics studies and hint at unanticipated peroxisomal functions are also highlighted. Knowledge gained from Arabidopsis was utilized to compile a tentative list of peroxisome proteins for the model monocot plant, rice. Differences in the peroxisomal proteome between these two model plants were drawn, and novel facets in rice were expounded upon. Finally, we discuss about the current limitations of experimental proteomics in decoding the complete and dynamic makeup of peroxisomes, and complementary and integrated approaches that would be beneficial to defining the peroxisomal metabolic and regulatory roadmaps. The synteny of genomes in the grass family makes rice an ideal model to study peroxisomes in cereal crops, in which these organelles have received much less attention, with the ultimate goal to improve crop yield.
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Affiliation(s)
- Navneet Kaur
- MSU-DOE Plant Research Laboratory, Michigan State UniversityEast Lansing, MI, USA
| | - Jianping Hu
- MSU-DOE Plant Research Laboratory, Michigan State UniversityEast Lansing, MI, USA
- Plant Biology Department, Michigan State UniversityEast Lansing, MI, USA
- *Correspondence: Jianping Hu, MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA. e-mail:
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24
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Theodoulou FL, Zhang X, De Marcos Lousa C, Nyathi Y, Baker A. Peroxisomal Transport Systems: Roles in Signaling and Metabolism. SIGNALING AND COMMUNICATION IN PLANTS 2011. [DOI: 10.1007/978-3-642-14369-4_12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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25
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Khan BR, Zolman BK. pex5 Mutants that differentially disrupt PTS1 and PTS2 peroxisomal matrix protein import in Arabidopsis. PLANT PHYSIOLOGY 2010; 154:1602-15. [PMID: 20974890 PMCID: PMC2996013 DOI: 10.1104/pp.110.162479] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 10/11/2010] [Indexed: 05/21/2023]
Abstract
PEX5 and PEX7 are receptors required for the import of peroxisome-bound proteins containing one of two peroxisomal targeting signals (PTS1 or PTS2). To better understand the role of PEX5 in plant peroxisomal import, we characterized the Arabidopsis (Arabidopsis thaliana) pex5-10 mutant, which has a T-DNA insertion in exon 5 of the PEX5 gene. Sequencing results revealed that exon 5, along with the T-DNA, is removed in this mutant, resulting in a truncated pex5 protein. The pex5-10 mutant has germination defects and is completely dependent on exogenous Suc for early seedling establishment, based on poor utilization of seed-storage fatty acids. This mutant also has delayed development and reduced fertility, although adult pex5-10 plants appear normal. Peroxisomal metabolism of indole-3-butyric acid, propionate, and isobutyrate also is disrupted. The pex5-10 mutant has reduced import of both PTS1 and PTS2 proteins, and enzymatic processes that occur in peroxisomes are disrupted. To specifically study the import and importance of PTS1 proteins, we made a truncated PEX5 construct lacking the PTS1-binding region (PEX5(454)). Transformation of this construct into pex5-10 resulted in the rescue of PTS2 import, thereby creating a line with PTS1-specific import defects. The pex5-10 (PEX5(454)) plants still had developmental defects, although restoring PTS2 import resulted in a less severe mutant phenotype. Comparison of pex5-10 and pex5-10 (PEX5(454)) phenotypes can separate the import mechanisms for enzymes acting in different peroxisomal processes, including indole-3-butyric acid/2,4-dichlorophenoxybutyric acid oxidation, isobutyrate and propionate metabolism, and photorespiration.
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26
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Nyathi Y, De Marcos Lousa C, van Roermund CW, Wanders RJA, Johnson B, Baldwin SA, Theodoulou FL, Baker A. The Arabidopsis peroxisomal ABC transporter, comatose, complements the Saccharomyces cerevisiae pxa1 pxa2Delta mutant for metabolism of long-chain fatty acids and exhibits fatty acyl-CoA-stimulated ATPase activity. J Biol Chem 2010; 285:29892-902. [PMID: 20659892 PMCID: PMC2943281 DOI: 10.1074/jbc.m110.151225] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 07/08/2010] [Indexed: 12/26/2022] Open
Abstract
The Arabidopsis ABC transporter Comatose (CTS; AtABCD1) is required for uptake into the peroxisome of a wide range of substrates for β-oxidation, but it is uncertain whether CTS itself is the transporter or if the transported substrates are free acids or CoA esters. To establish a system for its biochemical analysis, CTS was expressed in Saccharomyces cerevisiae. The plant protein was correctly targeted to yeast peroxisomes, was assembled into the membrane with its nucleotide binding domains in the cytosol, and exhibited basal ATPase activity that was sensitive to aluminum fluoride and abrogated by mutation of a conserved Walker A motif lysine residue. The yeast pxa1 pxa2Δ mutant lacks the homologous peroxisomal ABC transporter and is unable to grow on oleic acid. Consistent with its exhibiting a function in yeast akin to that in the plant, CTS rescued the oleate growth phenotype of the pxa1 pxa2Δ mutant, and restored β-oxidation of fatty acids with a range of chain lengths and varying degrees of desaturation. When expressed in yeast peroxisomal membranes, the basal ATPase activity of CTS could be stimulated by fatty acyl-CoAs but not by fatty acids. The implications of these findings for the function and substrate specificity of CTS are discussed.
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Affiliation(s)
- Yvonne Nyathi
- From the Centre for Plant Sciences, Faculty of Biological Sciences, and
| | | | - Carlo W. van Roermund
- the Departments of Pediatrics and Clinical Chemistry, Laboratory of Genetic Metabolic Diseases, Academic Medical Centre, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands, and
| | - Ronald J. A. Wanders
- the Departments of Pediatrics and Clinical Chemistry, Laboratory of Genetic Metabolic Diseases, Academic Medical Centre, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands, and
| | - Barbara Johnson
- From the Centre for Plant Sciences, Faculty of Biological Sciences, and
| | - Stephen A. Baldwin
- the Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | | | - Alison Baker
- From the Centre for Plant Sciences, Faculty of Biological Sciences, and
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27
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Borek S, Ratajczak L. Storage lipids as a source of carbon skeletons for asparagine synthesis in germinating seeds of yellow lupine (Lupinus luteus L.). JOURNAL OF PLANT PHYSIOLOGY 2010; 167:717-724. [PMID: 20170979 DOI: 10.1016/j.jplph.2009.12.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Revised: 12/14/2009] [Accepted: 12/14/2009] [Indexed: 05/28/2023]
Abstract
The (14)C-acetate metabolism and regulatory functions of sucrose and sodium fluoride (NaF) were examined in embryo axes and cotyledons isolated from yellow lupine seeds and grown in vitro. After 15 min of incubating organs in solutions of labeled acetate, more radioactivity was found in amino acids (particularly in glutamate, asparagine and glutamine) than in sugars. After 120 min of incubation, (14)C was still localized mainly in amino acids (particularly in asparagine and glutamate). The (14)C atoms from position C-1 of acetate were mostly localized in the liberated (14)CO(2), whereas those from position C-2 were incorporated chiefly into amino acids, sugars and the insoluble fraction of the studied organs. The addition of NaF caused a decrease in the amount of (14)C incorporated into amino acids and in the insoluble fraction. The influence of NaF on incorporation of (14)C into sugars differed between organs. In embryo axes, NaF inhibited this process, but in cotyledons it stimulated (14)C incorporation into glucose. The release of (14)CO(2) with the C-1 and C-2 carbon atoms from acetate was more intensive in embryo axes and cotyledons grown on a medium without sucrose. This process was markedly limited by NaF, which inhibits glycolysis and gluconeogenesis. Alternative pathways of carbon flow from fatty acids to asparagine are discussed.
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Affiliation(s)
- Sławomir Borek
- Department of Plant Physiology, Adam Mickiewicz University, Poznań, Poland.
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28
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Strijbis K, van Roermund CW, van den Burg J, van den Berg M, Hardy GPM, Wanders RJ, Distel B. Contributions of carnitine acetyltransferases to intracellular acetyl unit transport in Candida albicans. J Biol Chem 2010; 285:24335-46. [PMID: 20522553 DOI: 10.1074/jbc.m109.094250] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transport of acetyl-CoA between intracellular compartments is mediated by carnitine acetyltransferases (Cats) that reversibly link acetyl units to the carrier molecule carnitine. The genome of the opportunistic pathogenic yeast Candida albicans encodes several (putative) Cats: the peroxisomal and mitochondrial Cat2 isoenzymes encoded by a single gene and the carnitine acetyltransferase homologs Yat1 and Yat2. To determine the contributions of the individual Cats, various carnitine acetyltransferase mutant strains were constructed and subjected to phenotypic and biochemical analyses on different carbon sources. We show that mitochondrial Cat2 is required for the intramitochondrial conversion of acetylcarnitine to acetyl-CoA, which is essential for a functional tricarboxylic acid cycle during growth on oleate, acetate, ethanol, and citrate. Yat1 is cytosolic and contributes to acetyl-CoA transport from the cytosol during growth on ethanol or acetate, but its activity is not required for growth on oleate. Yat2 is also cytosolic, but we were unable to attribute any function to this enzyme. Surprisingly, peroxisomal Cat2 is essential neither for export of acetyl units during growth on oleate nor for the import of acetyl units during growth on acetate or ethanol. Oxidation of fatty acids still takes place in the absence of peroxisomal Cat2, but biomass formation is absent, and the strain displays a growth delay on acetate and ethanol that can be partially rescued by the addition of carnitine. Based on our results, we present a model for the intracellular flow of acetyl units under various growth conditions and the roles of each of the Cats in this process.
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Affiliation(s)
- Karin Strijbis
- Department of Medical Biochemistry, Academic Medical Center, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands
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29
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Kaur N, Reumann S, Hu J. Peroxisome biogenesis and function. THE ARABIDOPSIS BOOK 2009; 7:e0123. [PMID: 22303249 PMCID: PMC3243405 DOI: 10.1199/tab.0123] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Peroxisomes are small and single membrane-delimited organelles that execute numerous metabolic reactions and have pivotal roles in plant growth and development. In recent years, forward and reverse genetic studies along with biochemical and cell biological analyses in Arabidopsis have enabled researchers to identify many peroxisome proteins and elucidate their functions. This review focuses on the advances in our understanding of peroxisome biogenesis and metabolism, and further explores the contribution of large-scale analysis, such as in sillco predictions and proteomics, in augmenting our knowledge of peroxisome function In Arabidopsis.
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Affiliation(s)
| | - Sigrun Reumann
- Centre for Organelle Research, Faculty of Science and Technology, University of Stavanger, N-4036 Stavanger, Norway
| | - Jianping Hu
- MSU-DOE Plant Research Laboratory and
- Plant Biology Department, Michigan State University, East Lansing, MI 48824
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30
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Slocombe SP, Cornah J, Pinfield-Wells H, Soady K, Zhang Q, Gilday A, Dyer JM, Graham IA. Oil accumulation in leaves directed by modification of fatty acid breakdown and lipid synthesis pathways. PLANT BIOTECHNOLOGY JOURNAL 2009; 7:694-703. [PMID: 19702756 DOI: 10.1111/j.1467-7652.2009.00435.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Plant oils in the form of triacylglycerol (TAG) are used for food, industrial feedstock and biofuel manufacture. Although TAG is typically harvested from the fruit or seeds of oil crop species, plants can also accumulate small amounts of TAG in the leaves and other vegetative tissues. Here we show that leaf TAG levels can be increased significantly (10-20 fold) by blocking fatty acid breakdown, particularly during extended dark treatments or leaf senescence in the model plant Arabidopsis. Generation of a double mutant in fatty acid breakdown and diacylglycerol acyltransferase 1 (DGAT1) resulted in a severe vegetative growth phenotype suggesting that partitioning of fatty acids to TAG in leaves is carried out predominantly by this acyltransferase. LEC2, a seed development transcription factor involved in storage product accumulation, was ectopically expressed during senescence in the fatty acid breakdown mutant COMATOSE (cts2). This resulted in accumulation of seed oil type species of TAG in senescing tissue. Our data suggests that recycled membrane fatty acids can be re-directed to TAG by expressing the seed-programme in senescing tissue or by a block in fatty acid breakdown. This work raises the possibility of producing significant amounts of oil in vegetative tissues of biomass crops such as Miscanthus.
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Affiliation(s)
- Steve P Slocombe
- Centre for Novel Agricultural Products, Department of Biology, University of York, Heslington, York, UK
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Kunz HH, Scharnewski M, Feussner K, Feussner I, Flügge UI, Fulda M, Gierth M. The ABC transporter PXA1 and peroxisomal beta-oxidation are vital for metabolism in mature leaves of Arabidopsis during extended darkness. THE PLANT CELL 2009; 21:2733-49. [PMID: 19794119 PMCID: PMC2768912 DOI: 10.1105/tpc.108.064857] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 08/11/2009] [Accepted: 09/02/2009] [Indexed: 05/17/2023]
Abstract
Fatty acid beta-oxidation is essential for seedling establishment of oilseed plants, but little is known about its role in leaf metabolism of adult plants. Arabidopsis thaliana plants with loss-of-function mutations in the peroxisomal ABC-transporter1 (PXA1) or the core beta-oxidation enzyme keto-acyl-thiolase 2 (KAT2) have impaired peroxisomal beta-oxidation. pxa1 and kat2 plants developed severe leaf necrosis, bleached rapidly when returned to light, and died after extended dark treatment, whereas the wild type was unaffected. Dark-treated pxa1 plants showed a decrease in photosystem II efficiency early on and accumulation of free fatty acids, mostly alpha-linolenic acid [18:3(n-3)] and pheophorbide a, a phototoxic chlorophyll catabolite causing the rapid bleaching. Isolated wild-type and pxa1 chloroplasts challenged with comparable alpha-linolenic acid concentrations both showed an 80% reduction in photosynthetic electron transport, whereas intact pxa1 plants were more susceptible to the toxic effects of alpha-linolenic acid than the wild type. Furthermore, starch-free mutants with impaired PXA1 function showed the phenotype more quickly, indicating a link between energy metabolism and beta-oxidation. We conclude that the accumulation of free polyunsaturated fatty acids causes membrane damage in pxa1 and kat2 plants and propose a model in which fatty acid respiration via peroxisomal beta-oxidation plays a major role in dark-treated plants after depletion of starch reserves.
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Affiliation(s)
- Hans-Henning Kunz
- Department of Botany II, University of Cologne, 50931 Koeln, Germany
| | - Michael Scharnewski
- Department for Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Goettingen, Germany
| | - Kirstin Feussner
- Department of Developmental Biochemistry, Institute for Biochemistry and DFG Research Center for the Molecular Physiology of the Brain, Georg-August-University, Goettingen, Germany
| | - Ivo Feussner
- Department for Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Goettingen, Germany
| | - Ulf-Ingo Flügge
- Department of Botany II, University of Cologne, 50931 Koeln, Germany
| | - Martin Fulda
- Department for Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University, Goettingen, Germany
| | - Markus Gierth
- Department of Botany II, University of Cologne, 50931 Koeln, Germany
- Address correspondence to
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Metabolic control exerted by the 2-oxoglutarate dehydrogenase reaction: a cross-kingdom comparison of the crossroad between energy production and nitrogen assimilation. Biochem J 2009; 422:405-21. [PMID: 19698086 DOI: 10.1042/bj20090722] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mechanism-based inhibitors and both forward and reverse genetics have proved to be essential tools in revealing roles for specific enzymatic processes in cellular function. Here, we review experimental studies aimed at assessing the impact of OG (2-oxoglutarate) oxidative decarboxylation on basic cellular activities in a number of biological systems. After summarizing the catalytic and regulatory properties of the OGDHC (OG dehydrogenase complex), we describe the evidence that has been accrued on its cellular role. We demonstrate an essential role of this enzyme in metabolic control in a wide range of organisms. Targeting this enzyme in different cells and tissues, mainly by its specific inhibitors, effects changes in a number of basic functions, such as mitochondrial potential, tissue respiration, ROS (reactive oxygen species) production, nitrogen metabolism, glutamate signalling and survival, supporting the notion that the evolutionary conserved reaction of OG degradation is required for metabolic adaptation. In particular, regulation of OGDHC under stress conditions may be essential to overcome glutamate excitotoxicity in neurons or affect the wound response in plants. Thus, apart from its role in producing energy, the flux through OGDHC significantly affects nitrogen assimilation and amino acid metabolism, whereas the side reactions of OGDHC, such as ROS production and the carboligase reaction, have biological functions in signalling and glyoxylate utilization. Our current view on the role of OGDHC reaction in various processes within complex biological systems allows us a far greater fundamental understanding of metabolic regulation and also opens up new opportunities for us to address both biotechnological and medical challenges.
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Bibliography. Current world literature. Nutrition and metabolism. Curr Opin Lipidol 2009; 20:63-72. [PMID: 19106709 DOI: 10.1097/mol.0b013e32832402a2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Yazaki K, Shitan N, Sugiyama A, Takanashi K. Chapter 6 Cell and Molecular Biology of ATP‐Binding Cassette Proteins in Plants. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 276:263-99. [DOI: 10.1016/s1937-6448(09)76006-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Araújo WL, Nunes-Nesi A, Trenkamp S, Bunik VI, Fernie AR. Inhibition of 2-oxoglutarate dehydrogenase in potato tuber suggests the enzyme is limiting for respiration and confirms its importance in nitrogen assimilation,. PLANT PHYSIOLOGY 2008; 148:1782-96. [PMID: 18842826 PMCID: PMC2593666 DOI: 10.1104/pp.108.126219] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Accepted: 10/01/2008] [Indexed: 05/19/2023]
Abstract
The 2-oxoglutarate dehydrogenase complex constitutes a mitochondrially localized tricarboxylic acid cycle multienzyme system responsible for the conversion of 2-oxoglutarate to succinyl-coenzyme A concomitant with NAD(+) reduction. Although regulatory mechanisms of plant enzyme complexes have been characterized in vitro, little is known concerning their role in plant metabolism in situ. This issue has recently been addressed at the cellular level in nonplant systems via the use of specific phosphonate inhibitors of the enzyme. Here, we describe the application of these inhibitors for the functional analysis of the potato (Solanum tuberosum) tuber 2-oxoglutarate dehydrogenase complex. In vitro experiments revealed that succinyl phosphonate (SP) and a carboxy ethyl ester of SP are slow-binding inhibitors of the 2-oxoglutarate dehydrogenase complex, displaying greater inhibitory effects than a diethyl ester of SP, a phosphono ethyl ester of SP, or a triethyl ester of SP. Incubation of potato tuber slices with the inhibitors revealed that they were adequately taken up by the tissue and produced the anticipated effects on the in situ enzyme activity. In order to assess the metabolic consequences of the 2-oxoglutarate dehydrogenase complex inhibition, we evaluated the levels of a broad range of primary metabolites using an established gas chromatography-mass spectrometry method. We additionally analyzed the rate of respiration in both tuber discs and isolated mitochondria. Finally, we evaluated the metabolic fate of radiolabeled acetate, 2-oxoglutarate or glucose, and (13)C-labeled pyruvate and glutamate following incubation of tuber discs in the presence or absence of either SP or the carboxy ethyl ester of SP. The data obtained are discussed in the context of the roles of the 2-oxoglutarate dehydrogenase complex in respiration and carbon-nitrogen interactions.
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Affiliation(s)
- Wagner L Araújo
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476 Potsdam-Golm, Germany
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Dietrich D, Schmuths H, De Marcos Lousa C, Baldwin JM, Baldwin SA, Baker A, Theodoulou FL, Holdsworth MJ. Mutations in the Arabidopsis peroxisomal ABC transporter COMATOSE allow differentiation between multiple functions in planta: insights from an allelic series. Mol Biol Cell 2008; 20:530-43. [PMID: 19019987 DOI: 10.1091/mbc.e08-07-0745] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
COMATOSE (CTS), the Arabidopsis homologue of human Adrenoleukodystrophy protein (ALDP), is required for import of substrates for peroxisomal beta-oxidation. A new allelic series and a homology model based on the bacterial ABC transporter, Sav1866, provide novel insights into structure-function relations of ABC subfamily D proteins. In contrast to ALDP, where the majority of mutations result in protein absence from the peroxisomal membrane, all CTS mutants produced stable protein. Mutation of conserved residues in the Walker A and B motifs in CTS nucleotide-binding domain (NBD) 1 resulted in a null phenotype but had little effect in NBD2, indicating that the NBDs are functionally distinct in vivo. Two alleles containing mutations in NBD1 outside the Walker motifs (E617K and C631Y) exhibited resistance to auxin precursors 2,4-dichlorophenoxybutyric acid (2,4-DB) and indole butyric acid (IBA) but were wild type in all other tests. The homology model predicted that the transmission interfaces are domain-swapped in CTS, and the differential effects of mutations in the conserved "EAA motif" of coupling helix 2 supported this prediction, consistent with distinct roles for each NBD. Our findings demonstrate that CTS functions can be separated by mutagenesis and the structural model provides a framework for interpretation of phenotypic data.
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Affiliation(s)
- Daniela Dietrich
- Department of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
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Verrier PJ, Bird D, Burla B, Dassa E, Forestier C, Geisler M, Klein M, Kolukisaoglu U, Lee Y, Martinoia E, Murphy A, Rea PA, Samuels L, Schulz B, Spalding EJ, Yazaki K, Theodoulou FL. Plant ABC proteins--a unified nomenclature and updated inventory. TRENDS IN PLANT SCIENCE 2008; 13:151-9. [PMID: 18299247 DOI: 10.1016/j.tplants.2008.02.001] [Citation(s) in RCA: 459] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 01/21/2008] [Accepted: 02/14/2008] [Indexed: 05/18/2023]
Abstract
The ABC superfamily comprises both membrane-bound transporters and soluble proteins involved in a broad range of processes, many of which are of considerable agricultural, biotechnological and medical potential. Completion of the Arabidopsis and rice genome sequences has revealed a particularly large and diverse complement of plant ABC proteins in comparison with other organisms. Forward and reverse genetics, together with heterologous expression, have uncovered many novel roles for plant ABC proteins, but this progress has been accompanied by a confusing proliferation of names for plant ABC genes and their products. A consolidated nomenclature will provide much-needed clarity and a framework for future research.
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Affiliation(s)
- Paul J Verrier
- Biomathematics and Bioinformatics Department, Rothamsted Research, Harpenden, AL5 2JQ, UK
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Holdsworth MJ, Bentsink L, Soppe WJJ. Molecular networks regulating Arabidopsis seed maturation, after-ripening, dormancy and germination. THE NEW PHYTOLOGIST 2008; 179:33-54. [PMID: 18422904 DOI: 10.1111/j.1469-8137.2008.02437.x] [Citation(s) in RCA: 530] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The transition between dormancy and germination represents a critical stage in the life cycle of higher plants and is an important ecological and commercial trait. In this review we present current knowledge of the molecular control of this trait in Arabidopsis thaliana, focussing on important components functioning during the developmental phases of seed maturation, after-ripening and imbibition. Establishment of dormancy during seed maturation is regulated by networks of transcription factors with overlapping and discrete functions. Following desiccation, after-ripening determines germination potential and, surprisingly, recent observations suggest that transcriptional and post-transcriptional processes occur in the dry seed. The single-cell endosperm layer that surrounds the embryo plays a crucial role in the maintenance of dormancy, and transcriptomics approaches are beginning to uncover endosperm-specific genes and processes. Molecular genetic approaches have provided many new components of hormone signalling pathways, but also indicate the importance of hormone-independent pathways and of natural variation in key regulatory loci. The influence of environmental signals (particularly light) following after-ripening, and the effect of moist chilling (stratification) are increasingly being understood at the molecular level. Combined postgenomics, physiology and molecular genetics approaches are beginning to provide an unparalleled understanding of the molecular processes underlying dormancy and germination.
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Affiliation(s)
- Michael J Holdsworth
- Department of Agricultural and Environmental Sciences, School of BioSciences, University of Nottingham, Nottingham LE12 5RD, UK
| | - Leónie Bentsink
- Department of Molecular Plant Physiology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Wim J J Soppe
- Department of Plant Breeding and Genetics, Max Planck Institute for Plant Breeding Research, 50829, Cologne, Germany
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